/Engine/Source/Runtime/SlateCore/Public/Widgets/SWidget.h
Set a new accessible behavior, and if the behavior is custom, new accessible text to go along with it.
void SetAccessibleBehavior ( EAccessibleBehavior InBehavior, const [TAttribute](API\Runtime\Core\Misc\TAttribute)< [FText](API\Runtime\Core\Internationalization\FText) > & InText, EAccessibleType AccessibleType )